/**
 * export 使用as重命名
 * @param  {Number} x [description]
 * @param  {Number} y [description]
 * @return {[type]}   [description]
 */
function v1(x = 0, y = 0) {
  return x + y;
}


function v2(x = 0, y = 0) {
  return x - y;
}

export {
  v1 as add,
  v2 as sub,
};